Orientin Attenuated d-GalN/LPS-Induced Liver Injury through the Inhibition of Oxidative Stress via Nrf2/Keap1 Pathway

Oxidative stress is involved in the pathogenesis of liver diseases, including liver injury, a serious health problem worldwide. Natural polyphenols have attracted increasing attention as potential agents for the prevention and treatment of liver diseases. Orientin, a flavonoid component with antioxidant capacity, has been regarded as a promising nutraceutical for patients with liver damage. This study aimed to investigate the amelioration effect of orientin on d-galactosamine and lipopolysaccharides (d-GalN/LPS) induced liver injury in mice, with a focus on its underlying mechanisms by using the H2O2-induced oxidative damage model of HepG2 cells. Results indicated that orientin alleviated d-GalN/LPS-induced liver damage by improving the hepatic histological changes and reducing the levels of hepatic and serum alanine aminotransferase and aspartic acid aminotransferase. Additionally, supplementation of orientin improved the antioxidant ability in mice by decreasing the levels of hepatic malondialdehyde, protein carbonyl, myeloperoxidase, nitric oxide, glutathione, glutathione peroxidase, gluathione reductase, and superoxide dismutase. Orientin treatment significantly elevated both the protein and mRNA expressions of nuclear factor erythroid 2-related factor 2, Kelch-like ECH-associated protein-1, heme oxygenase-1, and nicotinamide quinone oxidoreductase 1 in liver and HepG2 cells. The management of orientin also elevated the protein expression of glutathione S-transferase and Maf in HepG2 cells. Taken together, it suggested that orientin played an amelioration effect on liver injury by suppressing oxidative stress, which might be strongly related to the activation of Nrf2/ARE through PI3K/Akt and P38/MAPK signal pathways.